ML17328A139
| ML17328A139 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 09/06/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17328A138 | List: |
| References | |
| NUDOCS 8909140218 | |
| Download: ML17328A139 (5) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D, C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO..I28TO FACILITY OPERATING LICENSE NO.
DPR-58 INDIANA MICHIGAN POWER COMPANY DONALD C.
COOK NUCLEAR PLANT UNIT NO.
1 DOCKET NO. 50-315
1.0 INTRODUCTION
Technical Specification (TS) Surveillance Requirement
- operable, on a sampling basis, by a combination of visual and functional tests.
Surveillance Requirement 4.7.8.c further specifies that snubbers which failed the previous functional test shall be retested during the next test period.
In August 1987, snubber 1-GRC-S519, which is located on the pressurizer spray line inside the pressurizer enclosure, was tested per the requirements of TS
, 4. 7. 8 and failed the functional test.
The functional test required the snubber to lock up at velocities between approximately 0.5 and 15. 1 inches/minute, but the snubber did not lock up until reaching a velocity of 16.3 inches/minute.
The licensee completely rebuilt the snubber per their own requirements.
Upon successfully passing the functional test, the snubber was declared operable.
However, the licensee failed to retest the snubber during the next test period, which was the refueling outage in the spring of 1989.
At 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> on Friday, September 1, 1989, the licensee discovered that they had neglected to perform the functional test of Snubber No.
1-GRC-S519 as required by TS and entered a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> action statement.
Consequently, the licensee requested an emergency TS change which would modify TS 3/4.7.8 such that functional testing of Snubber No.
1-GRC-S519 may be delayed until the next time the unit is brought to Mode 5.
Specifically, a footnote is added to Table 3.7-4 stating, "Functional testing of this snubber may be delayed until the first time the unit enters Mode 5 after September 4, 1989."
In a teleconference on September 6, 1989, the licensee agreed to add a statement to the footnote that would require functional testing of the snubber in conjunction with the scheduled ice condenser ice basket surveillance or when the unit is brought to Mode 5, whichever occurs first.
The staff reviewed the licensee's evaluation and in a letter dated September 1,
- 1989, granted a temporary waiver of compliance in order to evaluate and process the emergency TS change request.
This Safety Evaluation addresses that request.
- 2. 0 EVALUATION The licensee supplied information to support their TS change request in a letter dated September 1, 1989, and provided supplemental information in a letter dated September 6, 1989.
These submittals provided the information necessary for the staff's evaluation of the TS change.
The staff's evaluation is summarized in the following subsections.
- 2. 1 Reliabilit Of Rebuilt Snubbers No.
1-GRC-S519 is a 2 1/2" x 5" Grinnell snubber.
Twenty-one of these snubbers were tested in 1978.
Of the twenty-one tested, eighteen snubbers failed their as-found test and were rebuilt or adjusted.
The majority of the failures were due to high lock-up velocities (similar to failure of Snubber No.
1-GRC-S519 in 1987).
To date, none of the eighteen snubbers rebuilt or adjusted has experienced a
subsequent failure.
Snubber No.
1-GRC-S519 passed its functional test in 1978 and was not rebuilt until after it failed due to a high lock-up velocity (1.2 inches/
minute above limit) in August of 1987.
As stated previously, Snubber No.
1-GRC-S519 passed its functional test after being rebuilt.
The licensee has appeared to follow good practice in assuring that the snubbers were properly rebuilt.
The replacement parts for the snubbers are purchased as N-Grade and shelf life for seal materials is monitored to ensure out of date materials are not installed.
Reference to part numbers in the maintenance procedures also helps ensure that the correct part numbers are used.
Although the licensee failed to perform a functional test of Snubber No.
1-GRC-S519 in the 1989 spring refueling outage, a visual test was conducted.
The snubber passed the visual test with no indication of leaks or disturbances.
Based on the statements in the preceding paragraphs of this subsection, it would appear that there is reasonable assurance that Snubber No.
1-GRC-S519 would be capable of performing its required function,
- 2. 2 Conse uence Of Snubber No.
1-GRC-S519 Failure At the licensee's
- request, Grinnell evaluated the increase in the specified lock-up velocity and determined that there were no significant differences in the dynamic responses and that the snubber would have locked up as expected in response to a seismic event.
The staff accepts this assessment.
The PISOL
- code, which is used for seismic analysis of the piping system containing Snubber No.
1-GRC-S519, considers the snubber to be in a locked condition during both the operational basis earthquake (OBE) and the design basis earthquake (DBE) condition.
The piping analysis results remain valid unless (1) the.snubber does not lock up or (2) there is significant pin to pin displacement of the snubber prior to its lock-up.
Grinnell confirmed that the snubber would properly lock-up at a velocity of 16.3 inches/minute during an OBE or a DBE.
The licensee also determined that the maximum pin to pin displacement of a snubber at any locking velocity is not significantly different from the value at the factory setting and concluded that there will be no significant change in pin to pin displacement of Snubber No.
1-GRC-S519 based on the recorded velocity.
-3" Therefore, it appears that even if the snubber were to "fail" in a manner similar to that experienced during the 1987 functional test, it would still lock in response to a design basis seismic event, thereby precluding failure of the pressurizer spray line.
2.3 Extension Of Functional Test Interval In a letter dated September 1, 1989, the staff issued a letter that granted the licensee a temporary waiver of compliance.
That letter stated that the functional testing of Snubber No.
1-GRC-S519 shall be performed in conjunction with the TS Surveillance Requirement
- 4. 6. 5. 1. b. 2 (ice condenser) or sooner in the event of a forced outage requiring entry into Mode 5, or in any event, not later than December 31, 1989.
The December 31,
- 1989, date was specified with the understanding that the ice condenser ice basket surveillances were scheduled for December of 1989.
However, the licensee incorrectly supplied the staff with the date cot respondi'ng to scheduled ice condenser ice basket surveillance for Unit 2.
The ice basket surveillance for Unit 1 is scheduled for February of 1990, 3.0 EMERGENCY CIRCUMSTANCES By letter dated September 1, 1989, the licensee requested that this amendment be treated as an emergency
- because, unless
- approved, the plant would have to proceed to cold shutdown.
Shutting down to Mode 5 would result in additional thermal cycling of the unit. It is necessary to enter Mode 5 to remove Snubber No.
1-GRC-S519 for functional testing, because of combination of extreme temperatures in the area and ALARA considerations.
In accordance with 10 CFR 50.91(a)(5),
the licensee has explained that the need for an emergency TS change could not have been avoided since the missed functional test of Snubber No.
1-GRC-S519 was not discovered until 0800 on September 1, 1989, when the unit was operating at full power.
4.0 FINAL NO SIGNIFICANT HAZARDS CONSIDERATION
DETERMINATION The Commission s regulations in 10 CFR 50.92 state that the Commission may make a final determination that a license amendment involves no significant hazards consideration if operation of the facility, in accordance with the amendment, would not:
(1) Involve a significant increase in the probability or consequences of an accident previously evaluated; or (2) Create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) Involve a significant reduction in a margin of safety.
The proposed changes do not involve a significant hazards consideration because the operation of Donald C.
Cook, Unit 1 in accordance with these changes would not:
(1) Involve a significant increase in the probability or consequences of an accident previously evaluated.
Based on the experience with rebuilt snubbers and the fact that a snubber can marginally exceed the locking velocity limit associated with the functional test and still perform its intended function, there is reasonable assurance that Snubber No.
1-GRC-S519 would lock-up in response to a design basis earthquake.
In light of this fact and the low probability of an earthquake for this region, the staff has determined that the extension of the functional test until the scheduled time frame for the ice condenser ice basket surveillances (February, 1990) does not significantly increase the probability or consequences of an accident previously evaluated.
(2) Create the possibility of a new or different kind of accident from any accident previously evaluated; or The change involves no physical modifications to the plant nor any changes in plant operations.
As discussed previously, there is reasonable assurance that Snubber No.
1-GRC-S519 would perform its intended function.
Therefore, the change should not create the possibility of a new or different kind of accident from any previously evaluated.
(3) Involve a significant reduction in a margin of safety.
Because there is reasonable assurance that Snubber No.
j.-GRC-S519 would lock-up as required in response to an earthquake, this change would not result in a signficant reduction of a safety margin.
Even if the snubber marginally exceeded the functional test lock-up velocity, as in the August 1987 test, the snubber would have performed the required safety function.
Furthermore, the uncertainties in determining whether a change in margin has occurred are such that it cannot be concluded reasonably that the margin actually changed.
Therefore, the change is not considered a
reduction in a margin of safety.
Accordingly, the Commission has determined that this amendment to Facility Operating License No.
DPR-58 involves no significant hazards consideration.
5.0 STATE CONSULTATION
In accordance with the Commission's regulations, efforts were made to contact the State of Michigan.
The state representative was contacted and had no comments.
- 6. 0 ENVIRONMENTAL CONSIDERATION This amendment involves a change in the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 or a change in a surveillance requirement.
The staff has determined that the amendment involves no significant incr ease in the amounts, and no significant change in the types, of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational
radiation exposure.
The Commission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has been no public comment on such finding.
Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b),
no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.
7.0 CONCLUSION
Me have concluded, based on the considerations discussed above that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed
- manner, (2) such activities wi 11 be conducted in compliance with the Commission s regulations, and (3) the issuance of this amendment will not be inimical to the common def'ense and security or to the health and safety of the public.
Dated:
September 6,
1989 Principal Contributor:
J.
G. Giitter